The tolerance of feline corpus and cauda spermatozoa to cryostress

Epididymal sperm preservation can be used to avoid the total loss of genetic material in threatened species. Spermatozoa from the corpus, as from the cauda, are motile and can undergo capacitation. Thus, they can potentially be preserved for assisted reproductive technologies. However, cryopreservation of spermatozoa has a direct detrimental effect on sperm quality. The aim of this study was to compare the chromatin stability and the survival rate of spermatozoa from the corpus and cauda epididymis after cryopreservation. Epididymal spermatozoa were collected and cryopreserved from the corpus and cauda of 12 domestic cats. Sperm motility, progressive motility, membrane integrity, acrosome integrity, and DNA integrity were evaluated before and after freezing thawing. The average total number of spermatozoa collected from the corpus was lower (10.2 × 106 ± 7.4) than that from the cauda epididymis (24.9 × 106 ± 14.4; P = 0.005). The percentage of spermatozoa with intact DNA did not differ significantly whether it was collected from the corpus or cauda regions and did not decrease after freezing thawing in either region. However, motility of spermatozoa from both regions was affected by the freezing thawing process with a significant decline in motility after thaw compared with fresh spermatozoa. A significant difference in the percentage of motile sperm between the corpus and cauda was observed after the freezing thawing process (P < 0.001). Although sperm motility was lower in postthaw spermatozoa from the corpus epididymidis than from the cauda, the rate of the reduction did not differ between regions. This study indicates that the cryopreservation process does not have a negative effect on chromatin stability of feline epididymal spermatozoa. Spermatozoa from the corpus region have a similar freezability as spermatozoa from the cauda region. Therefore, preservation of spermatozoa from the corpus and the cauda epididymidis might be of value in preserving genetic material from endangered or valuable felids.